This paper focuses on the experimental study for investigating the performance for lap splice of hooked or headed reinforcement in beam with different depths. In the experiment, seven specimens, with its variables as the lap length of headed or hooked bar, the existence of stirrups, etc., was manufactured. Bending test was conducted. Lap strengths by test were compared with the theoretical model based on KCI2012. The result showed that the cracks at failure mode occurred along the axial direction to a headed bar. The initial stiffness and the stiffness after initial crack were similar for all specimens. For HS series specimens without stirrups, a 25% increase in lap length was increased 11.8~18.1% maximum strengths. For HH series specimens without stirrups, a increase in lap length did not affect the maximum strengths because of the pryout failure of headed bar. For HS series specimens, the theoretical lap strengths based on KCI2012 considering the B grade lap and the reduction factor for stirrup were evaluated. They are smaller than the test strengths and can ensure the safety in terms of strength capacity. For HH series specimens, the stirrups in the lap zone are needed to prevent the pryout behaviour of headed bar.

An experimental study was conducted to propose an improved joint in the beam with non-uniform depths of cross-sections. The tested joint detail consisted of headed bars and 180-degree hooked bars. The parameters are the splice length and the confinement effect of strrups in lap zone. The increase of lap length and the confinement detail of strrup reinforcement in the lap zone did not affect the initial stiffness. It can be concluded that the proposed joint detail would be applicable to practical design by using the load transfer mechanism by the effects of confinement details.